Base damage

The base damage of a weapon is a constant number that is fixed to a particular weapon. Damage does not depend on where on the target the attack hits, with the exception of weapons that critical hit on certain regions of the target.

Distance and randomness modifier

How damage is affected by distance.

The distance modifier is a number between 1.5 and 0.5 that sinusoidally decreases as the distance between the attacker and the target increases. The trough of the wave is at 1024 units, and all distances beyond 1024 are treated as 1024 for the purposes of damage calculation. In this formula, there is a random variation in the distance of ±102.5 units (shown in the graph around 512 units, as an example). This means that you may be treated as being up to 102.5 closer or farther than you actually are, for purposes of the formula. This is the 15% variation many players have heard of; it is not simply a 85–115% multiplier on the final damage.

The distance modifier is altered for Rocket Launchers, Stickybomb Launchers (when detonated within 5 seconds), Syringe Guns, Righteous Bison and Pomson 6000. When the distance used in the formula is less than 512 units, the damage ramp is flattened. As a result, the maximum damage you can have is 125% for Rocket Launchers, and 120% for Stickybomb Launchers, Syringe Guns, Righteous Bison and Pomson (shown by the maroon offshoot in the graph). In short, these weapons gain less extra damage from the distance modifier at close range, but still suffer from the same long-range damage penalty as the other weapons.

Conversely, the distance modifier for the Scout's primary weapons (excluding the Shortstop) have an increased damage ramp at close range, maximising at 175% normal damage at point blank, but keep the same default damage ramp at ranges of 512 or greater.

Weapons that fire projectiles, like the Rocket Launcher and Direct Hit, apply the distance modifier to damage based on the distance between the attacker and the target at the moment the projectile hits a target. This means that the point from which the projectile was fired is irrelevant when considering damage dealt by that projectile; only the final position of the attacker and the target matter.

Notes

The final distance used in the formula cannot go above 1024 or below 0.

On servers where random variation is disabled (with use of the server cvar "tf_damage_disablespread"), the effective distance used is 102.5 units less than the farthest possible random distance (that is, after being capped at 1024 units). This means that being farther than 921.5 units away is treated as being 921.5 units away; the normal cap is 1024, and 102.5 less than that is 921.5 units.

Critical modifier

A critical hit adds damage equal to 2 times the base damage, while a mini-crit adds 0.35 times the damage following falloff compensation.

Both critical hits and mini-crits check to see if the final distance is greater than 512: if it is, then any damage lost is offset by an equal increase in damage. The end result is that the weapon does not lose damage due to the distance modifier when the player is more than 512 units away; if the attack were not a crit or mini-crit, damage would continue to decrease out to 1024 units.

The extra damage added on by critical hits and mini-crits - including that from rampup or offsetting falloff - is of the "critical" type instead of the weapon's standard type (e.g. bullet or explosive). This affects the calculation of damage resistances.

Note: A backstab deals 2 times the victim's current health, but, under normal conditions, it also always crits, increasing the damage to 6 times the victim's current health.

While active, the Battalion's Backup protects team members from critical hits and mini-crits, treating them as normal damage instead. The Vaccinator's protective shield blocks 100% of critical damage from attacks of the selected type.

Damage types

Each weapon has an associated type of damage that it deals. Some weapons can deal more than one damage type at once; for instance, the Cow Mangler 5000's charged shot deals explosive damage as well as fire afterburn damage.

Bullet damage is typically associated with hitscan weapons, though the damage caused by most projectile impacts is treated as such as well (such as syringes, arrows and energy beams, excluding the Cow Mangler 5000's beam).

Explosive damage is usually caused by explosive projectiles. Players killed via explosive damage will often gib.

Fire damage is caused by both flaming weaponry and the afterburn they induce.

Fall damage is applied to players that hit the ground after too high and/or too fast a drop.

Crush damage results when a player has been sandwiched between two objects (such as between a closing door and the ground). Being killed by crush damage causes the screen to flash red.

Damage vulnerability, resistance, and blocking

A player may take a modified amount of damage due to certain items. These effects stack multiplicatively. "X% damage vulnerability" multiplies that kind of damage by 100% then adding X%, and "Y% damage resistance" multiplies that kind of damage by 100% then subtracting Y%; for example, the Chargin' Targe grants 30% explosive damage resistance, which means all incoming explosive damage is multiplied by 70%.

Because effects are stacked multiplicatively, combinations of effects result in a slightly different value than may be expected; for example, a Soldier with the Pain Train (10% bullet weakness) and an active Battalion's Backup (50% sentry resistance) has a combined resistance of 45% against Sentry bullets - as opposed to the 40% that would result from the effects being simply added together.

Some weapons imbue an effect which increases or decreases the damage received from certain types of weapons. These effects may either be applied as "on wearer" (having the item equipped in the loadout) or "while active" (actively wielding the item).